Amniotic Fluid Optical Density to assess gestation period??

The termination of pregancy (say decreased  foetal movements, possible F distress,  clinically less liquor ) . In such circumstance where the indication of induction of labour is borderline and induction of  termination is not so robust then  concerned obstetrician is in dilemma about preterm termination  foe mild induction. We  are aware that where dating USG/NT san is not done the calculation of exact EEDD is quite difficult so also induction of labour. We are aware that when dating scan is not dome and she comes Qute late in pregancy(say > 32 weeks) most of the obstetrician nowadays rely on  FL & Transcereballar  diameter are more predictive. But in rural areas such expert sonologist are lacking and resolution necessary for estimation of Transcereballar dia is not possible, Qute often either no sonology  is done in entire pregnancy   or AFOD & Maturity of foetus and timing of CS :-ignoring LS ratio: Skin is the last organ to mature, which is denoted by shedding of vernix from foetal skin surface in to AF, which  can be  measured in terms of AFOD(optical density of amniotic fluid o diagnose maturity in caes of uncertain LMP) OD is not for diagnosing Foetal distress,.  It is very simple, safe, and painless. Anybody can do with little training. This avoids many troubles and complications Meconium stained liquor before the onset of labour. Some academic body  have issued guidelines recommending  confirmation of lung maturity before elective induction of labour or CS, before completion of 38 completed weeks of gestation, to avoid iatrogenic prematurity and respiratory morbidity.

From 2003 onwards few people routinely take AF samples before elective induction or CS to avoid iatrogenic prematurity, when no sonology is dome is early months of preg .  But though some do Optical density we don’t do L/S ratio estimation which is costly cumbersome, results take long time, and which is not available everywhere. L/S ratio gives information only about lung maturity.  Many center  do AFOD estimation which is cheap, easily available anywhere and takes only less than 5min. AFOD gives the information about the completion of maturity, i.e., maturation of all systems.

In this process of AFOD estimation, we observed fascinating and very important scientific information.

About 10-11% of mothers do have varying degrees of meconium staining liquor . This percentage is not small. In other words every 10th woman is having meconium stained liquor before the onset or early labour. In majority of women the CTG, NST and Doppler are normal. In some women when sample was taken in the morning, it was thin meconium stained liquor. When CS was done in the same evening it was grade 2 or 3 meconium. It does mean that the hostile process is continuing.

Unfortunately the ultrasound cannot make out meconium staining in liquor. By ultrasound TV imaging of fore water we could observe some special pictures, but not conclusive. Thin meconium cannot be detected at al by USG. Neither meconium stained liquor is not a sign of foetal distress is not correct. Foetal distress is an intermittent process. A foetus manifesting distress when uterus acting, may pass meconium and may recover on its own when the uterine activity comes down spontaneously or by tocolytics.  While carrying out AFOD , if one  detect meconium in AF while doing AFOD estimation, even if everything (CTG, BPP, and Doppler) is normal, one  cannot send the women home assuming meconium staining liquor is harmless.

Safety of amniocentesis: Amniocentesis at term is a simple and very safe procedure, as many superficial pockets which do not contain cord or placenta are available. One can safely use 23G,  2.5cm long IM needle to draw sample . Only < 5 mm length of the needle  enters pocket. One AF sample collection before elective induction or C.S is having so many advantages.

• Avoids induction on already distressed foetus, if liquor is meconium stained.
• Helps to assess the functional maturity status of foetus by AFOD estimation. If premature we can postpone induction/CS
• Also helps to predict when the foetus is going to attain completion of maturity. Accordingly one can  program labour.
• If AFOD is mature one need not give steroids. They do not develop RDS irrespective of GA.